(a) Field of the Invention
This invention relates to certain 4-oxo-4H-quinolizine-3-carboxylic acids and derivatives thereof (also known as quinolizinones) that are useful in the treatment of bacterial infections. In particular, this invention relates to a method of treating bacterial infections with said compounds. This invention further relates to pharmaceutical compositions containing said compounds and to a method of treating bacterial infections with said pharmaceutical compositions.
A multitude of broad spectrum antibiotics useful in the treatment of both Gram-positive and Gram-negative bacterial infections, as well as other microbial infections, are known. However, a continuing need for new antibiotics exists. For example, known antibiotics may be effective against only certain strains of microorganisms. Furthermore, and perhaps more seriously, continued widespread use can give rise to resistant strains of microorganisms against which a particular antibiotic or group of antibiotics was previously effective. The compounds of this invention were discovered as part of a search for new antibiotics intended to overcome such problems.
(b) Prior Art
Certain quinolizinone carboxylic acid derivatives are known. For example, Y. Kitaura et al., European Patent application 0157346, have disclosed compounds of Formula A: ##STR1## wherein R.sub.1 is inter alia carboxy or cyano; R.sup.7 is hydrogen or aryl; R.sup.2 is hydrogen, hydroxy, lower alkyl, or lower alkoxy; and R.sup.3 is inter alia hydrogen, hydroxy, lower alkyl, lower alkoxy, and optionally substituted aryl; and wherein R.sup.2 and R.sub.3 can be located at any position in the quinolizinone ring. The compounds are reported to exhibit antiallergy and antiulcer activities. The European patent application, however, neither discloses nor suggests antibacterial activity.